I know that you may have already done this but without knowing what the defects are, I would change the battery. On the black pro pointer, mud would occasionally get stuck under the rubber button that protects the on/off switch. This will cause the pointer to get stuck in the on position or prevent you from engaging the on switch. You can remove the button carefully and wash it off.
Also, remove any dirt from the switch opening. Do not allow water to get inside the unit.
Garrett has an Excellent "After sales service reputation. " If your pointers are only 6 months old, they will repair or replace your units at no charge.
That has been my experience.